Regenerative radio receiver



REGENERAT IVE RADIO RECEIVER Filed July 51,' 1955 INVENTOR ERNST KLOTZ ATTORNEY LEA ' the produced audio-frequency to the control grid Patented Nov. 2, 1937 art sts REGENERATIVE RADIO RECEIVER Ernst Klotz, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany, a corporation of Germany Application July 31, 1935, Serial No. 33,999 In Germany July 25, 1934 frequency circuit 3, a coil l2 connected between the anode A and the cathode of tube l, and in series with a resistor i3 bridged by a condenser i i. The anode furthermore, is connected galvanicaliy to the control grid, through a high-frequency filter consisting of resistor l5 and condenser 2i and also the resistors E8, ll and I8. A condenser is may be shunted across resistor ll as shown. If condenser i3 is of large capacity, grid 8 will be supplied with an audio voltage substantially equal to the audio voltage at the left hand end of resistor 56, while the direct current bias potential impressed on grid 3 is less than the direct current output voltage of resistor it in the ratio of the resistor 33 to the sum of resistors i? and 3d. In this way the direct current bias may be reduced and hence the automatic volume control action reduced independently of the audio frequency reflexing. The audio frequency developed at the left hand end of I6 is divided between resistors l8 and 23 and by making resistor 23 considerably larger than resistor iii, the larger fraction of the audio voltage at the anode A may be fed back to grid 8. Condenser 2! is small so as to by-pass any radio frequency currents passing through resistor l5 to ground. It will be seen that the portion of the tube including anode A and cathode forms a diode detector of the amplified radio frequency voltage impressed on secondary winding E2, the derived audio frequency voltage being transmitted to the control grid 8 through the resistor-condenser filter circuit lfil9. The normal grid bias may be produced by the bias resistor 22 and the grid 8 connected to ground through a high resistance 23. Having described my invention, what I claim as novel and desire to secure by Letters Patent is: 1. A combined amplifying and detecting device for modulated high frequency signal currents comprising the combination of a vacuum tube having a cathode, an anode and a signal control grid and a second grid located in the electron stream between said anode and cathode, means for impressing the signal currents on said control grid, an output circuitconnected to said second grid and including the series connection of a high resistance and a coil, a condenser having a low impedance to currents of the modulation frequency connected to one end of said resistance, a connection between said anode and cathode including the series connection of ,a resistor and a second coil, said coils being inductively coupled together, and a direct current connection between said anode and cathode and including at least two resistors connected in series,

6 Claims.

This invention relates to a receiver circuit for wireless telephony, in which in one stage, high frequency amplification as well as detection and audio-frequency amplification is obtained.

Circuits are already known in which a single tube performs these three functions. In this case the tube is a rnulti-grid tube whose outermost grid serves as an anode for the amplification path, while for the detection function the diode path consisting of cathode and actual anode, is used. In series with the diode path, a high frequency impedance is placed for coupling the high frequency circuit placed in the output circuit of the outer grid and a transformer for transmitting circuit, is also placed in series to the diode path.

In accordance with the invention, there is arranged between cathode and the outermost electrode, a resistor, bridged by a condenser and connected in series to the coupling element of the circuit of the grid electrode acting as anode, and there is suitably provided a galvanic or conductive connection between the anode of the diode and the control grid, across suitable high-frequency filter or smoothing means. The advantage thereby follows that the drop of the direct potential, produced by the detection of the high frequency, can be additionally utilized for controlling the control grid in the sense of a fading control.

The subject matter of the invention Will now be illustrated with reference to the circuit shown in the accompanying drawing by way of example and in which I denotes an electron tube equipped with four grids. The outermost grid 2 serves as the anode for the amplification path. It is connected to the cathode across the tuned highfrequency circuit 3 and to the resistor 4 serving as load for the detected modulation currents. The potential drop across the resistor d is for instance applied to the grid of the following tube, by means of a coupling condenser ii. The grid 5 serves as a suppressor grid and is connected with the cathode. Grid l is the screen grid and has a steady positive potential applied relative to the cathode. The innermost grid 8 is connected with the tuned input circuit i3 through a coupling condenser 9, the input circuit being fed with the modulated high-frequency energy from a primary coil II. Condenser 9 has a low impedance to currents of the carrier frequency but is not large enough to appreciably by-pass the audio frequency voltage developed to ground through the coil 24 of circuit l0.

There is coupled to the inductance of the highsaid resistors being arranged to also transfer the modulation potentials of said anode to said signal control grid.

2. A combined amplifying and detecting device for modulated high frequency signal currents comprising the combination of a vacuum tube having a cathode, an anode and a signal control grid located in the electron stream between said cathode and anode, a condenser having one side connected to said signal control grid and its other side to the source of signal currents, an output circuit connected to said second grid, a circuit connected to said anode and cathode and including a feedback connection to said output circuit and a circuit arranged to transfer the modulation potentials of said anode to said signal control grid and also providing a direct current connection between said anode and cathode and including at least two resistors connected in series and a condenser having one side connected to the common terminal of said resistors and its other side grounded.

3. A combined amplifying and detecting device for modulated radio frequency currents comprising the combination of a vacuum tube having a cathode, an anode, a signal control grid and a second grid, means for impressing the signal currents on said control grid, an output circuit including an inductance coil connected to said second grid, a connection between said anode and cathode including the series connection of a resistor and a second coil, said coils being inductively coupled; a condenser shunted across said resistor and an additional circuit connecting said anode and control grid and arranged to cause the voltage of said control grid to vary in accordance I with the modulation voltage variations of said anode. I

4. A combined amplifier and detecting device for modulated radio frequency signals comprising in combination a vacuum tube having a cathode, a control grid, a second grid and an anode, means for impressing the signal voltage variations on said control grid, an output circuit connected to said second grid, a circuit connected to said anode and cathode and including a feedback connection to said output circuit and a circuit arranged to transfer the modulation potentials of said anode to said control grid and including the series connection of at least one resistor and a condenser connected between said anode and control grid 5. In combination in a combined amplifier and detecting device, a vacumn tube having a, cathode, a signa1 control grid, a second grid and an anode, an input circuit resonant to the signal frequency connected to said control grid, a resonant output circuit connected to said second grid, a feedback connection between said resonant circuit and said anode and including a resistance, a condenser shuntingsaidresistance,meansfortransferringthe modulation potentials of said anode to said control grid comprising at least two resistors connected in series between said anode and control grid and a circuit conductive to direct current connected between the common terminal of said resistors and said cathode and including a high resistance.

6. A combined amplifying and detecting device for modulated radio frequency signal currents comprising the combination of a vacuum tube having a cathode, an anode, and a signal control grid and a second grid located in the electron stream between said cathode and anode, a condenser having one side connected to said signal control grid and its other side to a source of signal currents, an output circuit connected to said second grid, a circuit connected to said a anode and cathode and including a feedback connection to said output circuit, an impedance conductive to direct current having one end directly connected to said signal control grid, an impedance conductive to direct current having one end directly connected to said anode and a condenser having its opp site sides connected respectively to the other ends of said impedances, said condenser and impedances providing a path between anode and signal control grid having a low impedance to currents of the modulation frequency.

ERNST KLOTZ. 

